The present invention relates to an improved chain saw guide bar. The bar of a conventional chain saw has a weight which is a fairly large proportion of the total weight of the chain saw, and it is cantilevered from the engine housing. Japanese Utility Model Early Publication S.63-188101 laid open on Dec. 2, 1988 shows a guide bar formed with relatively large holes therethrough, in which synthetic resin or other lightweight material is embedded, to reduce the bar weight. However, the large holes through the bar weaken it, and the embedded material is exposed on both sides and may therefore be released from the bar after long use.